Progress in HIV Vaccine Research Leads to Insight on Disease Mechanism

This article was written by Volunteer Blog Writer Beverly F. Spencer. If you are interested in being a writer for The A Word, please visit: http://www.aidscalgary.org/getinvolved/volunteer/volunteeroverview.cfm

For years Scientists at the Oregon Health & Science University have been experimenting with potential HIV vaccine developments in hopes of better understanding how HIV functions within the human immune system. Ascribing to its highly elusive nature, it has proven to be no easy task to effectively target the disease. However, recent discoveries published in the May issue of the Science journal,  have shed light on a promising new candidate that appears to behave both as a prophylactic and antidotal entity.

Coming back to this elusory quandary, this issue has been one of the major road-blocks which scientists have been challenged with, in their pharmaceutical strategies. T-cells, particularly CD8+ T-cells, serve to identify and manage virus-infected cells through short viral peptide recognition which are found on the surface of these cells. Once these peptides are marked, the T-cells execute a cytotoxic reaction to eliminate the infection. Here inherently lies the elusory element. CD8+ T-cells have a limited number of short viral peptides which they can sufficiently determine and respond to and while some of the highly vicissitudinous HIV viral peptides do become the subject of target, the ones critical for cell survival evade detection.

The name of the game, then, seems obvious: to cast the net wide and capture these vulnerable viral peptides. In theory, widening the scope of detection markers would eventually lead HIV to fall prey to cell destruction. By allowing CD8+ T-cells to recognize a larger variety of these short viral peptides, they should be able identify the crucial peptides needed to render the virus incapacitated.

Ironically, it is through another virus, cytomegalovirus (CMV), which may serve to accomplish this task. Using SIV, an animal mirror-virus of HIV, researchers were able to  reconstruct CMV to produce SIV-specific proteins which showed surprising results. SIV-specific T-cells emerged which contained a recognition breadth of viral peptides that far exceeded what regular T-cells could do independently including the attempts of prior vaccines.  What was even more interesting about this engineered response was that it was able to target viruses which had previously evaded extermination which means this vaccine may prove to be useful in a two-front powerhouse attack on the endeavor to eradicate HIV.

Although the concept of a customizable therapeutic agent, such as the CMV vehicle, may create potential for a viable future vaccine to hit the market, there is still a long way to go before human clinical trials can begin its initial phase.  However, the new information has proved useful as the research findings in themselves gave the medical community an invaluable perspective on the relational functionality between the human immune system and the HIV disease. This will hopefully improve the interim therapeutic model until clinical trials can be brought to the agenda.

References:

Science Daily. (2013). Promising Strategy to Help Vaccines Outsmart HIV. Retrieved from: http://www.sciencedaily.com/releases/2013/05/130524122012.htm

Appay, V., Nixon, D.F., Donahoe, S.M., Gillespie, G.M.A., Dong, T., King, A., ... Rowland-Jones, S.L. (2000). HIV-Specific Cd8+ T Cells Produce Antiviral Cytokines but are Impaired in Cytolytic Function. The Journal of Experimental Medicine, 192 (1), 63-76. doi: 10.1084/jem.192.1.63